Multiple Input Multiple Output (MIMO) can increase the efficiency of data transmission and reception using multiple transmit antennas and multiple receive antennas. According to MIMO, a transmitting end or a receiving end of a wireless communication system uses multiple antennas to improve communication capacity or performance. MIMO can also be called a multi-antenna technology. For successful multi-antenna transmission, it is necessary to feedback information on a multi-antenna channel from a receiving end that receives the multi-antenna channel.
In a conventional multi-antenna wireless communication system, a rank indicator (RI), a precoding matrix index (PMI), channel quality indicator (CQI), etc. are defined as information fed back to a transmitting end from a receiving end. This feedback information is configured as information suitable for conventional multi-antenna transmission.
Introduction of a new system having an extended antenna configuration compared to the conventional multi-antenna wireless communication system is under discussion. For example, a new system having an extended antenna configuration can provide improved system capacity by supporting MIMO transmission through 8 transmit antennas, whereas the convention system supports up to 4 transmit antennas.